Follow-up valve control means for hydraulic mechanism



F. T. COURT Aug. 15, 1950 FOLLOW-UP VALVE CONTROL MEANS FOR HYDRAULIC MECHANISM '7 Sheets-meet 1 Filed Nov. 9, 1945 ATTORNEYS.

F. T. COURT Aug. 15, 1950 FOLLOW-UP VALVE CONTROL MEANS FOR HYDRAULIC MECHANISM 7 Sheets-Sheet 2 Filed Nov. 9, 1945 ENTOR. DE C E 5 FR ANK T COU R E D ATTORNEYS.

' Aug. 15, 1950 F. 'r. COURT 2,519,228

FOLLOW-UP VALVE CONTROL MEANS FOR HYDRAULIC MECHANISM F. T. COURT FOLLOW-UP VALVE CONTROL MEANS FOR HYDRAULIC MECHANISM 7 Sheets-Sheet 4 Filed Nov. 9, 1945 s R r m m N X R HER m NST T U A F. T. COURT Aug. 15, 1950 FOLLOW-UP VALVE CONTROL MEANS FOR HYDRAULIC MECHANISM '7 Sheets-Sheet 5 Filed Nov. 9, 1945 INVENTOR. FRANKT COURT, DECEASED VIRGINIA FCOU T, EXECUTRIX A ETORNEYS.

F. T. COURT 2,519,228

UP VALVE CONTROL MEANS FOR HYDRAULIC MECHANISM Aug. 15, 1950 '7 Sheets-Sheet 6 FOLLOW Filed Nov. 9, 1945 INVENTOR. FRANK T COURT DECEASED E EGUTRIX F. 'r. couR'r Aug. 15, 1950 FOLLOW-LIP VALVE CONTROL MEANS FOR HYDRAULIC MECHANISM Filed NOV. 9, 1945 7 Sheets-Sheet '7 INVENTOR/ qgoEA SE EXECU IOO 'RANKTC URT \EIRGINIA E cou relented Au 15,1950

UNITED STATES PATENT OFFICE".

' 2,519,228 I p i FOLLOW-UPV'ALVE CONTROL Fort HYDRAULIC MECHANISM Frank '1; Court, deceased, late of Moline, 111., by

Virginia F. Court; executrix, Moline, 111., assignor to Deere div Company, Moline, IHL, a'corA poration of Illinois- Application November 9, 1945, Serial' No. 627,681

The present: invention relates generally .tohydraulic powercontrol mechanism and has for its principal object the provision of a novel and improved hydraulic mechanism, which is more sensitively and more accurately. controlled than similar mechanism heretofore known -tothose skilled invthe art, and yet which" is simple' and inexpensive to manufacture: and strong; and durable in operation.

Another object of theinvention relates'to the provision of a hydraulic power control mechanism havinga manually, adjustable control lever for-controlling the movement of the mechanism inaeither direction, the operation of which is closelycsimilar :tothat of an ordinary manually controlled lever connected directly to'a load. In

this. type-of hydraulic system,- the control lever is moved by the operator in one direction orthe other, depending upon whichedirection be: desires to mOVG'thC'IDadL The control lever moves at arate which is proportional to the speed of movement of the load and as long as'theoperator exertsasmallamount of force against thecontrol lever, while the-load is being moved-bya hy-.

draulic. motor. .When the operator releases presthe. end of a row or--furrow and steering it'into.

alignment with the next row? or, furrow. In the accomplishment of this object; the control level is provided withlatching means, which holds the control valve in active position to cause the hydraulic motor to operate, but without'afiecting the movement of the control lever proportional to the movement of the load.

Arelated object has to do with the provision of adjustable stop means against which-the control lever engages, when it is bein moved to shift sure from the-control lever, the motor as wellas the control lever-stops immediately. Thus,;the operation of the control lever in this type of hydraulic system" is similar to the movement-of: an ordinary handlever connected directly to-the load which moves as long as the operator exerts,

pressure against it but stopsimmediatelyupon release. The only difference in operation is that the actual force required'to movethe load is exertedby a separate. source of power, rather than bythe actual pressure exerted-by the operator;

A system" of this type is :valuable for the purpose of adjusting agricultural-implements associated with a tractor, inasmuch asoperators of this type of .equipmentarefamiliar withthe operatiton of ordinaryshandadjustin levers, so thata hydraulicmechanism of this type requires practically no additional training-in its operation Under certainoperating conditions, such as when adjusting theoperating, position of a tractor mounted implement,- it is desirable to have the hydraulic motor operate slowlyinorder to facilitate anaccurate-adjustment ofthe implemenaibut under other conditions, such-as when raising" the implement a to a transport position, it is: desirable to-have the hydraulicmechanism operate-as quickly possible. Another objectof the: .present invention, therefore, relates; to the provision'ofmeans for controlling the speed of responsaofthehydraulic. motor the-position of a load, the engagement of the lever with the stop thereby causing the control valve. to stop the movement of the hydraulic motor and thus to arrest the movement of the load at anyparticular predetermined position; This feature is valuablein insuring that the implement will always be returned to the predetermined working .depthfafter the tractor has been turned around at the endof the field, and this feature is operative either while the operator is maintaininga pressure against the control lever, or when the lever is latched in its active position. Still. another object of the present invention relates to the provision for automaticallydunlatchingthe control lever and stopping the hydraulic motor at anypoint in case the pressure in the hydraulic system increases above a predetermined maximum, such as when the "implement may/encounter an'obstruction during its movement'by the hydraulic motor. In the. accomplishment. of this object, the mechanism which latches the control valve in active position is'connected with the excess pressure relief valve insuch a manner that an actuation of the relief valve unlatches the latching mechanism.-

These. and. other objects and advantages of the present invention will be apparent" to those skilledjn the art after a consideration of the following descriptionin which reference is had to the drawings appended hereto, in which:

Figure 1 isla rear. elevational view ofthe central portion of a tractor rear axle housing, showing hydraulic power control mechanism embodying the principles of the present invention;

Figure. 2 is a sectional elevational view taken 3 along a fore and aft extending vertical plane indicated by a line 2-2 in Figure 1;

Figure 3 is a sectional plan view taken through the hydraulic control valve housing along a line 3--3 in Figures 2 and 4, and drawn to an enlarged scale;

Figure 4 is an elevational view taken along a line 4-4 in Figures 2 and 3;

Figure 5 is a sectional elevational view taken along a line 5--5 in Figure 3; t

Figure 6 is a sectional elevational view taken along a line 65 in Figure 3;

Figure 7 is a view similar to Figure 6 but showing the valve mechanism in latched position in one direction of operation;

Figure 8 is a fragmentaryelevational View of the latch mechanism as in Figure 7, but with the control lever and valve latched in the oppo site direction; and

Figures 9 and 10 are sectional elevational views of the control valve mechanism taken along a line 9-9 in Figure 4 and drawn to an enlarged scale, and show four different positions of the control valve mechanism during operation.

Referring now to the drawings, and more particularly to Figures 1 and 2, the tractor is indicated by a portion of its body including a. banjotype rear "axle housing 20, comprising an enlarged centrally disposed gear housing 2| and a pair of oppositely extending axle housing quills 22 formed integrally therewith. The quills 22 contain a pair of coaxially disposed drive axles 23, the inner ends of which carry drive gears 24 disposed within the gear housing portion 2!, and the drive gears 24 are driven from the engine of the tractor by suitable mechanism, the details of which are not shown since they are well known to those skilled in the art. The gear compartment 2i of the axle housing 29 i pro-' formed with a transversely disposed bearing sleeve 29 in the upper portion thereof within which is journaled a conventional rockshaft 30, the two ends 3! of which extend laterally from the ends of the sleeve portion'29 and are of substantially square cross section for the purpose of receiving implement controlling and lifting arms (not shown), as is well known to those skilled in the art.

The rockshaft 351 is actuated by a rocker arm 35 fixed to a hub 36 secured to the rockshaft 3E The rocker arm 35 extends downwardly'and is pivotally connected by a pin 31 to a piston rod 38. The piston rod 38 extends forwardly and is connected to the piston 39 of a fluid pressure motor 40 by means of a wrist pin 4|. The fluid I pressure motor 40 comprises the piston 39 and :of the housing 25, the latter having a duct formed integrally therewith in register with th cylinder duct 43.

The construction so far described is identical with the hydraulic mechanism disclosed in Patent 2,302,637 granted November 17, 1942, to Mc- Cormick and Hansen, to which reference may be had for a more complete description of this part of the apparatus. As in the patented structure, the housing 25 also includes an integrally formed reservoir 46 for the hydraulic fluid and also a conventional gear pump indicated generally by reference numeral 41, whch is secured by bolts 48 to the rear side of the housing 25. One of the pump gears (not shown) is mounted on the tractor power take-off shaft 49, which extends rearwardly from a suitable connection with the tractor engine and is journaled in a bearing 59 beneath the reservoir 46 and formed integrally with the housing 25. The power takeoff shaft 49 extends rearwardly through the pump 4'! and has a splined rear end portion 5! for supplying power to implements associated with a tractor, in a manner well known to those skilled in the art. The pump 47 receives fluid from the reservoir 46 and discharges the same under pressure through a high pressure duct 52 extending upwardly through the reservoir 46, as disclosed in the above-mentioned patent.

Coming now to that portion of the apparatus with which this invention is particularly. concerned, a control housing is secured to the rear side of the rockshaft housing 26 by means of a plurality of bolts 6|, which extend through apertures '52 in the control housing fitland engage suitable threaded apertures (not shown) in the housing 25. The control housing 60 is provided with an opening 63in its forward side, which is disposed in register with a corresponding open ing 53 in the rear side of the housing 25, thereby communicating with the reservoir 46 in the latter.

Although the control valve mechanism and its details of construction and operation form no part of this invention, except generally in combination with other elements of the system as defined in the appended claims, a rather detailed description thereof is deemed necessary to a thorough understanding of that phase of the invention disclosed and claimed here. The valve mechanism is disclosed and claimed in co-pending divisional application, Serial No. 785,026, filed November 10, 1947, now Patent No. 2,505,527.

The control housingfifl is provided with a cored high pressure passage 64 provided with an intake port 55. The passage 64 extends upwardly from the port 65 and turns laterally, as indicated at 66 (see Figure 3). The passage 66 turns rearwardly at El and again laterally at 68, from which it divides into two branches curving upwardly and downwardly toward the rear of the housing 60, as indicated at 69 and 70, best shown in Figure 5. The two branches 69 and ill terminate in a pair of annular ports H, 72 in a vertically extending cylindrical valve chamber TI. The valve cylinder H is also provided with a pair of annular exhaust ports l3, l4 spaced from the supply ports H, 12, respectively. The exhaust ports l3, 14 are connected in communication with the interior of the housing 60, and hence with the reservoir 46. Between each pair of adjacent supply and exhaust ports 1!, l3, and l2, 14 is a motor supply port l5, 16, respectively.

A valve member 30 in the form of a generally cylindrical plunger is slidably disposed within the valve cylinder 11. The plunger fits closely within the cylinder to prevent flow of hydraulic fluid along the valve cylinder 11 but is reduced in diameter at two axially spaced regions 8|, 82, thereby defining three spool or piston portions 83,

eg-traces 8 4$ 85 Whe'1i the val veljplungefiBuds in its centered neutral or inactive position, showman-Figores-j i and :5; l the centralpiston portion 84 extendsbe'tweemthe two fluid supplyports TI;- 12,

"while the portions 81-; '82 of reduced diameter extend between the supply ports II, I2: andnthe adiacent exhaust ports I3,- 14,: pr-ovidinguclearance for the hydraulicflu'id to flow'fromleach: of

the 'branches -69; -I 0 along theereduced diameter pertions -8I,- 83 and out through the exhaust port rn; I4; returning to-the .reservoirdh The valve plunges 80 can be shifted; upwardly in-the valve cylinder 'II until the lower; piston portion 85 -blocks the valve' cylinder aborentheilower "exhaust per-c. 14 thereby preventing. escapecoi the fluid tromthe branch: duct TIL-while the center piston tit moves into blocking. relation. inthe upper'supply port-J I, preventing the flowof fluid I through-the upper branch duct 69; thereby directm menunmm the pump-into-the lowen motor supply-port Tilt-land connecting the upper .motor supply:port l iig with the exhaust port Conversely, whenthe vvalve plunger. 83-=is1shitted downwardly in the cylinder- 11,. the upper piston portion-B3 closes the exhaust port :I 3;-preventing fluid fromflowingupwardly from the upper branch duct- 69;: whereupon the-fluid is directed into the-'upper motor supply port. I5. Simultaneouslyg the' lower: edge of-thelcentr-al. pistonportion-84 blocks the lower branch duct. Ifl while the;lower motor. supply port I6 is-connected with the-lower exhaust port I4;

A pair aof 'closur-e members 90; 9 I are positioned in the valvecylinder I I outwardly of the exhaust ports 13 14, respectively, defining compartments vided1with adrilledopening ill-extending axially therethrough! to receive the stem "9810f. a poppet type'jcheck valveoi which thereare two provided,

98;, I08; all-opposite ends of the valve mechanism, respectively. Each of the check valves-99,\ IIlll isseated in an annular seating member ID I ,which is. pressed into a suitable. recess in outwardly spacedrclationlto the adjacent closure member 93 oreQI toldefine Hie outer end of the compartment 92: or; 93;respectively. Eachof the;checkrvalves 39,. Illa-is urged. into engagement with its seat Illtnhy means of a compression spring I05, disposedin upper and lower-.check valve chambers 4116,uI OIrandcreacts against a plug N38. The two plugs .II'I8 are threaded into the upper and. lower endslo'fi the -.ver,tical passageway through the housing castingifilhwhich forms the valve cylinder &1, thesscompartments 92,. 93,;and the check-l valve chambers-z I 0dr. I01; Each of the compartments 92;93isconnected with the adjacent motorsup- :plyzport 15 ,1"\'|6;by meansofa by-pass duct H19, It'll; respectively, the ;.by.-pass ducts l serving to convey hydraulic; fluidfrom the valve cylinder II, 1 around. the .exhaustports 13, 14 tothe .compartmentsl 92;; 93.5 respectively.

- 1 The hydraulicrmechanismadisclosed hereinlcan beeusedsfomeither amizetwo purposes; first it cam-be used to controlithe rockshaft fim -by means of theinte'gra/l cylinder 400: secondgiit canbeused to-control a remotely disposed; fluid motorindicated generallybyreferencenumeral l I5 in Figure. 5. The fluid motor ll'5 cornprises a. cylinder I I G and a piston -I I I sli'dable axially therein and connected to an actuating rod I I8 which extends outwardly through a packing gland I-I:9' in-the closed end of the cylinder. A- connector; I201 is provided on the BndOf't'hB'piSItOn rod -I I B for .connecting the-latter toiimplements. associated with the-tractor,- The'opposite endsofsthe cylinder-.116 isalso closed. by means of a cylinder head I24, which is formed I integrally with amounting. lug I25 providedfo'r attaching-the cylinder to the associated' implement." The fluid motor. I I.5.1 isof the double actingl type, which providesioru fluid to-- be conducted under pressure into either: end of the cylinder for the purpose of-forcing the-piston II! .in either. direction within the cylinder H6. The head I24 islprovided with a fittinglIZG for introducingfluidunder pressure into one'end of the cylinder, while-another fitting: I2T'is provided. for. introducing-fluid under pressureinto a duct I28 formed integrally with the cylinder H6 and extending axially: along thelattenanmcommunicating. with the opposite endrof the cylinder 'bore; Each of'the fittingsIZG, I21 is provided,

with alflexiblelhose I29, I3Il,-.the.two hoses being detachably connected;- with the hydrauliccontrol mechanismby means of apair of bayonet.- connectors.|33; I342;

Each of the. connectors [33; I34 comprisesa tubular memberl35 adaptedto-beslidably inser-table intonupperaand.rlower horizontal passages I36- inthe;rear. wall of thecontrol housing 69, into; theevalvelchambersal 06,1 IIl'I.;;respectively. annular. sealing. memberl3l. isprovided for sealing: eachof the passages I 35; against leakage offoil therefrom-,each-ofv the sealing members I3! beingdisposed-zwithin acylindrical. neck. I 38 ,which is rigid with: the housing 60 and is, externally threaded to receive a clampingtcollar I39. which has anlinwardly turned securing flange 140.; The tubular member I35 is providedW-ith-a head; I43 which!is circumferentially grooved at I to receive a segmental or,.split;a washer I45," which is adapted tosbe; clamped between -.the collar I39 andthe end;ofthe neck I38, to hold the connector I35 within its socket. Thewashergl li can be made of frangible material, so that itwill break in the,.event thatthe draft connection between v the implement and the tractor isi broken and an attempt is made to move the tractor away from the; implement without disconnecting the motor.

supp-lynport 12:;doWnw-ardly through the. motor supply port ,16 .and the lay-pass. duct IIU .toathe compartment 93, in which the pressure of theoil .forces. open the lowercheck: valve I OH, whereupon the, oil flows past the valve "lull through the tubularmemberl35 of the lower connector; I33,f;and then through'the flexible hose. I29, causing the cylinder and pistonrod IIB to be extended. This ,forcesthe oiloutof the opposite end of the cylinder lificthrough the duct I28, flexible. hose-I30, and connector I34 to theuppercheck valve chamber I961. The upper check valve 99 has been raised awapfrom its seat. IIl'Il by upward-'movement-of lthezvahre plunger ;;in a-manner-tobe described later, whereu on the fluid returning from the cylinder I I 6 passes under the open check valve 99,

.through the upper. check valve 99 and hose I to the lower end of the cylinder I I6, as viewed in Figure 5. Movement of the piston II1 upwardly within the cylinder IIS forces fluid through the hose I29, connector I33, and upwardly through the lower check valve I06, which is opened responsive to downward movement of the valve plunger 80 in the valve cylinder 11, as will be explained. The fluid then flows upwardly through the by-pass duct H0 and supply port 16, back to the reservoir through the lower exhaust port 14.

The single acting hydraulic motor 60 is connected through the supply ducts 43, through a passage I50, which is formed integrally with the control housing 00 and communicates with the lower check valve chamber I01. A shut off valve I5I is provided in the passage I50, and can be of any suitable form such as a vertical cylindrical member I52 extending upwardly through the passage I and journaled above and below the latter, the member I52 being adapted to completely block the passage I50 but having a diametrically extending aperture I53 which, as shown in Figure 5, is positioned transversely of the passage I50, wherefore the latter is blocked by the cylindrical member I52, but when the member I 52 is turned through an angle of 90 degrees, the aperture I53 is aligned with the passage I50 and conducts the fluid therethrough. The cylindrical member I 52 is provided with a head I54 beneath the housing 60 for the purpose of turning the cylinder I52 to open or close the valve, and the upper end of the valve member I5I is provided with a threaded end portion I55 of reduced diameter, which is adapted to receive a nut I56 for securing the valve member I5I in position. Sealing washers I51 revent leakage of oil out of the passage I50 along the valve member I 5!.

When the double acting remote cylinder H5 is connected to the control housing 69, the shut off valve I5I is positioned with the aperture I53 transversely of the passage I59 in order to pre vent flow of fluid to the integral cylinder 40. However, when it is desired to operate the rockshaft 30 by means of the integral cylinder 40, the remote cylinder II5 should be disconnected by unscrewing the two collars I39 and withdrawing the connectors I33, I34. The passages I36 should then be closed to prevent oil from flowing out through the necks I38 by any suitable means, such as by closure caps I58, shown in Figures 1, 2, 3, 6 and '1. The valve l5I should then be opened by turning the cylindrical member I52 to align the aperture I53 with the duct I50.

The piston 39 in the integral cylinder 42 is forced rearwardly by pressure within the latter, responsive to an upward movement of the valve plunger 00, which directs fluid from the lower branchIIJ and supply port 12 downwardly through. th lower check valve I00 and along the passages I 50, 45, and 43, to the cylinder 42. Likewise, to lower the implement, the valve plunger 80 is shifted downwardlywithin the valve cylinder 11, to open the lower check valve I00 and allow the fluid to flow from the cylinder 42 upwardly through the by-pass duct III] and port 15, to be released through the exhaust port 14 to the reservoir.

While the oil is being returned from the cylinder 42 to the reservoir, the fluid output of the pump 41 is being directed upwardly through the upper branch 69 of the supply duct, through the upper supply port 15 and by-pass duct I09 into the compartment 92. The pressure of the fluid forces open thecheck valve 99, permitting the oil to flow into the check valve chamber I06. Provision is made for returning the fluid from the check valve chamber I06 to the reservoir, inasmuch as the closure cap I58 prevents flow of fluid out through the neck I38, and this provision takes the form of a vertical return duct I59, which intersects the horizontal passage I36 intermediate the ends of the latter and extends downwardly therefrom. The lower end of the return duct I59 intersects the lower horizontal passage I36, thereby returning the fluid from the pump to the lower check valve chamber I01, where it joins the flow from the integral cylinder 42 and is returned through the exhaust port 14 to the reservoir. A check valve I60 is disposed within the duct I59 and is urged upwardly by means of a compression spring I6I to a seat I62 within the duct I59, thereby preventing any flow of fluid upwardly through the passage I59 when the piston 39 is being forced rearwardly in the integral cylinder 42 under pressure. The check valve 150 is opened however by fluid flowing down through the passage I59 during the return movement of the piston 39 forwardly in the cylinder 92.

It will be noted that the tubular connectors I35 close off both ends of the passage I59 while the double acting motor H5 is being used. The upper and lower ends of the passage I59 are closed by plugs I93, I64, respectively. The re,- active force of the compression spring I9I is taken on a snap ring I65 seated in the wall of the passage above the connector I35.

The valve plunger is shifted upwardly and downwardly within the valve cylinder 11 by means of a gear member I10 rotatably disposed within a cylindrical chamber l1I between the two branches 59, '10 of the supply duct 68. The chamber I1I intersects the vertical valve cylinder 11 and the gear member I10 is provided with teeth along one side of the periphery thereof, which extend into the valve cylinder 11 and mesh with a short rack I12 formed in the central piston portion 84 of the valve plunger. Thus, by rotating the gear member I10 through a limited angle in either direction from a central neutral position, the valve plunger 80 can be shifted upwardly or downwardly within the cylinder 11 to its active positions for controlling the fluid motor associated therewith. The gear member I10 has an end portion I13 of reduced diameter which extends laterally out of one end of the cylindrical passage I1I, as is best shown in Fig ure 3. A hub I14 is fixed on the spindle portion I13 of reduced diameter and is formed integrally with a rearwardly extending actuating arm I15. The arm I15 is connected by a pivot pin I16 to alink I1 I which extends upwardly therefrom and is pivoted at I18 to a crank arm I19, which is rigidly mounted on a shaft I80. which is 101.11!

I92 extend between the legs 299 in gripping relation on opposite sides of the pin I91. When the valve plunger 89 is in its neutral or inactive position, the arms I9I, I92 grip the pin I91, as shown in Figure 6, near the outer ends of the arms outwardly of the notches I98. When the control lever I83 is moved rearwardly to adjust the implement downwardly, the arm pivot I19 is moved downwardly with the valve actuating arm I15 about the axis of the stub shaft I 13 and gear member I19. The upper arm I91 is free to swing angularly about the 'axis of the shaft I13, but the lower arm I92 is prevented by the latch pin I91 from swinging about the axis of the shaft I13, as will be evident in Figure '7. ISI, I92 to be spread apart against the pressure of the tension spring I95, with the result that when the lever I83 is released, the spring I95 acts to close the arms I9I, I92, thereby swinging the pivot pin I16 upwardly and. returning the valve and the control lever I83 to the neutral position.

Simiarly, when the control lever I83 is actuated forwardly from neutral position, the lower arm I92 swings about the stub shaft I13 out of engagement with the latch pin I91, while the upper arm I9I bears against the latch pin I91 and is separated from the lower arm I92 against the action of the spring I95. Hence, it will be evident that the centering device I98 acts by the force of the spring I95 to return the valve member 80 and control lever I93 to neutral or inactive position from either direction of actuation.

If the lever I83 is shifted in either direction to actuate the valve member 89 to its extreme position, the latch pin I91 receives the outer notch I98 in the'arm with which it is engaged. This causes the control lever I83 and the valve member 80 to be retained in the extreme position after the operator has released the control lever.

This is desirable in cases where the implement is to be raised or lowered to the end of the stroke of the piston 39, thereby relieving the operator of the necessity for holding the control lever until the implement i completely raised or lowered. However, the operator can easily disengage the latch pin I91 from the notch I99 at any time.

The temporary retention of the parts in the positions shown in Figure 8, for example, is accomplished as follows, all references to right and left hand sides and directions of movement being made with respect to Figures 2, 6, 7 and 3: Fundamentally, the pin I13 is fixed. The pin I91 is fixed, except when displaced to the right by operation of the pressure relief valve 299, which result may be disregarded for the moment; hence, the distance between I13 and I91 is normally fixed. The distance between the pin I16 and the pin I13 is fixed by the arm I15. On the other hand, the distance between the pin I19 and the pin I91 is variable as the pin I18 moves in its arcuate path about I13.

When the parts are in neutral positions (Figures 2 and 6), the extreme left hand ends of the arms I9I and I92 rest respectively on diametrically opposed upper and lower sides of the pin I91, and the notches I93 in the arms engage the pin I13, the arms being urged together by the spring I95. Assume now that the lever I83 is rocked forwardly short of its extreme position: The link I11 will move the pin I18 upwardly, thus shortening the distance between I13 and I91; and the left hand end of the arm I9I rides forwardly on the top of the pin I91. The parts are now approaching the positions of Figure 3 This causes the arms tween I13 and I91.

" stop 2M in the slot 2I3.

and the notch I96 in the upper arm I9I has not yet engaged the pin I 91. Hence, the parts are not yet'latched and the spring I95 can return them to neutral.

However, continued forward rocking of the lever I83 results in continued upward movement of the pin I18, further shortening the distance between I18 and I91. Consequently, the notch I99 in the upper arm I9I now engages the pin I91 and fixes the distance between I18 and I91. The distance between I16 and I13 is fixed, as is the distance between I 13 and I91, as aforesaid. Therefore, we have a temporarily rigid triangle I 91I19-I13, the structure of which depends on the notch I96 of the upper arm I 9| and action of the spring I95.

It will be seen, now, that any tendency of the pin I16 to move downwardly would result in a tendency to increase the distance between I16 and I91, which result is resisted by engagement of the notch I99 of the upper arm I9I with the pin I 91. Collapse of the temporary triangle is otherwise opposed by the fixed distance between I18 and I13 and the normally fixed distance be- The operator may, at will, destroy the triangle by moving the lever I83 rearwardly, thus forcing the notch I95 in the arm I9I to release its hold on the pin I91. As will hereinafter appear, operation of the pressure relief valve 298 to shift the pin I91 will also effect collapse of the triangle.

When the integral fluid motor 49 is being controlled, provision is made for automatically returning the control lever I83 to neutral position when the implement reaches a predetermined position during movement in either direction. Referring to Figure 2, a guide plate 2 I2 is mounted rigidly on the tractor adjacent the control lever I83 and is provided with an arcuate slot 2I3,

in which are secured a pair of adjustable limit stops 2M, 2I5 in the form of bolts extending through the slot 2 I3 and having thumb nuts for tightening the bolts in any position of adjustment along the slot 2I3. The stops 2M, 2I5 are adapted to engage the control lever I83 as the latter is shifted angularly by rotation of the bearing member I9! as it is rotated by the link I84. After the control lever I83 has engaged one of the stops 2H1 or 2I5, further movement of the bearing member I8I causes the actuating arm I15 and valve member 89 to be returned to neutral position, thereby arresting movement of the piston 39. For example, assume that the operator swing the control lever I83 forwardly until the notch I96 in the upper arm I9I of the centering device I99 engages the latch pin I91, as in Figure 8. This causes the piston 39 to be moved rearwardly in the cylinder 43, shifting the rocker arm 35 in a counterclockwise direction, as viewed in Figure 2, with a similar movement of the bearing member IBI, carrying the shaft I89 downwardly and rearwardly and swinging the control lever I83 forwardly until it engages the forward Continued movement of the piston 39 rearwardly, with the lever I83 against the stop 2M, tends to move the lever I83 rearwardly about the axis of its supporting shaft I89, thereby disengaging the notch I96 in the arm I9I from the latch pin I91, whereupon the spring I95 returns the valve member 89 to neutral position. The control lever I83 is now inclined forwardly adjacent the forward stop 2I4 but has been retracted slightly rearwardly therefrom by the centering action of the spring I95. The consalaries trol lever I83- can now be actuated rearwardly. to

I81 disengages the notch I96 from the latchpin- I91, permitting the spring- I95 to center the valve member 80.

Normally, the stop 2I 4 wouldnot be used for limiting ...the raising movement of the implement, for, it is customary to raise the implement'to the fuil extent-of :movement of the rockshaft 30 for transport purposes. However, it is desirable to limit the extent of downward movement-of the implement, for example, to control the depth ofoperation of a cultivator or plow. At the end of each-row or furrow the implement lmust'be raised to :permit the tractor to be'turned, after which theimplementis again lowered -to -the ground engaging position. Thus, by setting-the stop 2I5-in the appropriate position in the slot 2'-I3,.the implement will always be returned to the predetermined working -position, although the latter can be changed easily at anytime by shiftingltheistop ilfiralong the slot 2I 3.

- :When "theipiston 39 is allowed'to be forced under pressure to the extreme end of its range of movement, the rear endof the piston rod '38 'engages the wall-of the duct 64 in the housing casting fim thereby causing the pressure to rise in the hydraulic system. This 'increased pressure forces therelief-valve 200 rearwardly away from its seat, and since the latch =pin =I 91 is mounted on the valve-meniber'290, the pin 19-1 is shifted relative to the notch I96, whereupon the spring I 95 causes the centering device I90 to shiftthe valve member 80 to neutral position. Specifically, this result is achieved as follows, reference being had now to-Figurefl: As previously stated,-the locking of themechanism results from thetemporary-triangle defined by I91, I16 and I13,-the lock depending in part on fixing the distance between I91 and I16. #Whenthe-pin I91 is moved to the rightflit unseats from the notch I96in the" arm I92 and-the distance between I91 and H6 is no longer fixed. 'The arm-I92 then fulcrums on the shifted'pin r I 91 at a point to the right of the notch I96. As the pin I91 moves to the right out of the-notch I96, it cams the-arm I92 down-' wardly, adding to "the existing tendency of the spring I95'to jpulldown on the arm I9I, and

pivoting said arm in a counterclockwise direction about I13 to raise the"pin"I16-the natural. pivot for the parts. At the same time, the pinjl'91, in leaving the-notch, also exerts'a rearward push'on I92 which further'tends to raise I16. The parts, havingbeen' started inthis manner, continueito their neutral positions and the notchl93 in the lower...arm I92 seats .again onthepin'l13 .(the

notch I93 of the arml'9l"having been already seated). "When the pin I91 movesback to'the left underextension of the spring 296, it. cannot again. immediately reengage either notch I96,

since the relationship between .the pin I13 and arms I9I and ['92 is such as to prevent that.

result, as will be clear from Figure 6. The relief valve 200 will operate in this manner to unlatch the controlilever and shut ofi the .fiowof .oil to the cylinder at any time during the stroke of the pistonr. in the event "that 'the "load .Ion the 14 rockshart should .aexceedi a 'certainzmaximumwr in casethe implementxbeing :raisemencountersan obstruction-which prevents .furtherupwardrnovement. Thus the. relief valve 299: not only serves thespurpose of immediately relieving thepressure in. the:supply:;duct '64 by.;clischarging oil from/the endof the .;passage 20I, but alsoto center the control valve'and thereby. reducingthe pressure in the .entire'. system.

Whentheadouble acting remote cylinder 1 I5 is in use, the control lever I83idoes :not move angularly as the pistonzmoves intheoylinder, since non-.nsezoflthe ,piston ;?.9= efiects immobility thereof and cconseduently immobilizes the link,

I84and member-.I8I; .but the controlclever 1183 can nevertheless be latched in active positiomfor movement. of-thepiston ineitherr-direction, selectively. When the piston II-1reaches either end of the cylinder 1 I6, .however, the increase of hydraulic ,pressure in ,Ithe..system will -.cause the relief valve 200 .to .urrlatch the latch i mechanism and;.permit thewspring .:I 95 to centerwtheoperatingarm I1-5aand valve 580.

Obviously, the pressure relief valve 29,0.is-\available at all times to relieve an:.-excess.:pressure in latching device. is eneaaedor disengaged.

iIt-TiS desirable, whensmaking accurate :adjustmerit .of the: implement. associated with the :tractor, that -thefi-uidemotor 6.0 operate at a slower rate.of-.;speed than' when the implement isbeing raised totransport gposition. :Hence, it iszdesirable to 'providemeansifor gradually increasing ithe .pressuretapplied to the cylinder ti by means of :the-control lever 183. For this purpose a bleed hole 220'- is-:provided.in=the supply ductv portion 68, and isadapted toregisterxwith a'lbleed duct :22 I in the, gear. member I 1:6, best :shown in Figures :3 and Q5. .The :ableed ziuct (221 zBXtEIIGS radially inwardly.:from-.;the :cylindrical. surface of the. gear :memberz I119 and extends axially of the latter andrhas-an adjustable valvel222 in the end o .;the member I19. .Beyondthe seat of the valve 222, the duct .22I is in communication with the reservoir :between the .gear teeth of the member I10 and :the valve 15-222 can be adjusted by :a screwdriver inserted through an "opening @223 in the: side of the hous'ingiififl :in line with the valve member 222. A plug-224 normally'closes the adjustinghole 223 against'entrance ofdirt'and moisture. Thus, the valve 222 is adjusted to permit a sufiicient amount of oil= to leak or bleed from the high pressure duct-68, to reduce the hydraulic-'pressure-in the latter and thereby cause the-piston 39 to move more" slowly in the cylinder 42. Theaperture22Il and-duct 22L howeverpare disposed in'alignment only when'the controllever I83 is at or near the neutral posi- "tion,'1"or by'moving the'lever I93 in a direction thefluid motor 40 to obtain maximum speed from thelatter.

.The construction of the novel valve plunger and associated parts, will now be described,v in connection withFigures'Q andlO. The valve plunger "80 is 'hollow, 'being provided with an axially extending cylindrical passage 125, the

outerends of which have portions .226, 221 of larger diameter for receiving the inwardly extending cylindrical portions 96 of the closure members 99, 9|, respectively. Each of the inwardly extending cylindrical portions 99 of the closure members is provided with a peripheral groove 228, in which is disposed a resilient annular sealing member 229 adapted to slid-ably engage the inner surface of the associated passage 226 in the plunger 89 and prevent flow of fluid between the closure member and the end of the axial passage 225.

Disposed within the passage 225 is a piston member 233 which fits closely but slidably within the passage 225 and is provided with a pair of head portions 234 at opposite ends thereof, respectively, of larger diameter. The head portions 234 are slidably disposed within the end portions 226, 221 of the passage 225, of comparatively large diameter. The piston 233 is composed of two halves having a threaded joint 235 to facilitate assembly, and the piston 233 is provided with an axially extending bore 236 therethrough, disposed substantially coaxially with the passage 225 and plunger 89.

As explained herein before, the check valves 99, I99 have stems 98 which extend inwardly through passages 97 in the closure members 99, 9|, respectively, and into the enlarged end portions 226, 221 of the passage 225, where the inner ends of the check valve stems 98 are adapted to be engaged by the adjacent ends of the piston 233, respectively. The piston 233 is provided with radially extending passages 231, 238 at the inner end of the enlarged head 234. The passages 231, 238 communicate with the axial bore 239. Near each end of the valve member 89 is disposed an annular port 239, 249 extending around the inner surface of the enlarged end portions 226, 227 of the passage 225. The ports 239, 249 are provided with openings which communicate with the valve cylinder H at points within the reduced diameter portions 8!, 82 of the valve plunger 89.

The operation of the valve mechanism just described, will be explained in connection with the double acting cylinder H9. Figure 9 shows the valve mechanism disposed with all parts in neutral or inactive position. The valve plunger 39 is centered within the valve cylinder 17 and the piston 233 is centered within the valve plunger 89. It will be noted that there is a small clearance between each end of the piston 233 and the inner end of the adjacent check valves 99 and I99. Each of the annular ports 239, 249 is closed by the adjacent head 234 of the piston 233. In this position of the valve, the hydrdaulic fluid flows through the branches 99, 79 of the supply duct, along the reduced diameter portions 8|, 92, of the plunger, and returns to the reservoir through the exhaust ports l3, 14. Now assume that the control lever E33 is shifted forwardly to raise the valve member 89 to direct the oil through the lower connector I93 and hose I29 to the cylinder I H3. The valve plunger 89 is moved upwardly carrying with it the piston 233 until the end of the latter engages the inner end of the stem 98 of the check valve 99. As the plunger 89 is moved slightly upwardly the inner edge of the spool portion 99 closes the exhaust port 14, while the edge of the intermediate spool portion 84 closes the intake port ll. This causes pressure to build up in the branch duct 19, the cylinder supply port 76, the by-pass duct H9, and in case there is any air or vapor in the remote cylinder I I or its hose connections, the fluid flows through the check Valve I99 and compresses the air or gas in-the' 1'6 cylinder, for it will be noted that the check valve 99 has not yet been opened and therefore the fluid has not yet been released from the cylinder 399. Thus, it will be evident that the pressure in the hydraulic system builds ,up to the value necessary to open the pressure relief valve 299, and this pressure is applied to the outer side of the check valve 99 tending to hold the latter closed. Therefore, it is necessary to overcome this pressure in order to open the checkvalve 99 and permit the fluid motor I 15 to begin operation. If the check valve 99 were to be opened manually through the control lever I83, it would require considerable short on the part of the operator, but according to the principles of the present invention, this is accomplished hydraulically to relieve the operator. 3

This is accomplished by shifting the valve plunger 89 slightly farther upwardly, and since the piston 239 is in abutment with the end of the stem 98 of the check valve 99, the plunger 8-9 can be moved relative to the piston 233 until the annular port 249 is uncovered by moving it beyond the inner edge of the adjacent piston head 239. The valve parts are now in the position illustrated in Figure 19. Oil under pressure now flows through the annular port 249 and through the radial passage 239 into the inner bore 239 of the piston 233, and into the enlarged space 22'! between the closure member 9| and the adjacent piston head 234. The pressure in the space 221 is now equal to the pressure of the oil on the head of the check valve 99, but it will be noted that the area of the end of the head 239 of the piston 233 is appreciably larger than the area of the head of the check valve 99, and therefore the total pressure against the piston tending to open the check valve 99 is greater than the pressure resisting the opening of the check valve, with the result that the piston 233 and check valve99 begin to move upwardly. The fluid does not run out of the other end of the inner bore 299 into the space 226 between the closure member 99 and the upper end of the piston 293 for the reason that the inner end of the stem 98 of the check valve 99 closes the upper end of the bore 239 and prevents passage of oil therethrough. v

As the piston 239 and check valve 99 move upwardly the inner edge of the lower piston head 234 cuts off the fluid flow through the annular port 249, thereby stopping the opening movement of the upper check valve 99. The valve parts are now in the position illustrated in Figure 11 with the annular port 229 closed and the check valve 99 cracked open. Attention is called to the fact that the upper annular port 239 is not quite closed by the upper piston head 234 so that there is no hydraulic lock to prevent upward movement of the piston 233 in the passage 225. Hence, it is evident that the check valve 99 can be opened in as small increments of movement as desired, which are controlled by the increments of movement of the valve plunger 99 which is under the manual control of the operator. Since the entire pressure necessary to open the check valve 99 acts against the lower head of the piston 233 and reacts against the inner end of the lower closure member 9|, there is substantially no effort required by the operator to open the valve 99. As the operator continues to move the valve plunger upwardly, the piston 293 is moved upwardly to raise the check valve 99 whenever the lower annular port 249 is uncovered by the piston head 234 to permit fluid to flow through the radial aperture 239, the inner bore 239'into the to return said control arm and valve member to said intermediate inactive position.

5. In hydraulic mechanism, the combination of a fluid pressure motor comprising an extensible cylinder and piston assembly, a control valve therefor including a member shiftable in relatively opposite directions from an intermediate neutral or inactive position to'a pair of active positions effecting extension and contraction of said cylinder and piston assembly, respectively, means controlling said 'valve member comprising a control arm shiftable angularly about an axis, a lever connected to said control arm for shifting the latter, a support on which said lever is swingably mounted, means rotatably supporting said support, means connecting said support to said motor to be rotated thereby to shift said lever by movement of said cylinder and piston in gripping engagement with said stop means and said stationary element and limit stop means engageable with said lever during movement thereof in either direction by movement of said su port, thereby disengaging said latching means and permitting said valve member to be shifted to said neutral position by said biasing means acting through said pair of arms.

6. In hydraulic mechanism, the combination of a fluid pressure motor comprising an extensible cylinder and piston assembly, a control valve therefor including a member shiftable in relatively opposite directions from an intermediate neutral or inactive position to a pair of active positions effecting extension and contraction of said cylinder and piston assembly, respectively, means controlling said valve member comprising a 'control arm shiftable angularly about an axis, a lever connected to said control arm for shifting the latter, a support on which said lever is swingably mounted, means rotatably supporting said support, means connecting said support to said motor to be rotated thereby to shift said lever by movement of said cylinder and piston assembly while said lever is in either of said active positions in the same direction in which said lever is moved from said neutral position, disengageable latching means for retaining said lever and valve member in either of said active positions and for biasing the same toward said inactive position comprising a pair of arms pivotally mounted on said control arm outwardly of said axis, stop means mounted on said control arm in a position to be straddled by said pair of arms, a normally stationary element mounted ad- 3 jacent said control arm, said pair of arms straddling both said stop means and said normally stationary element, and having biasing means urging said pair of arms in opposed gripping engagement therewith, each of said pair of arms having means alternatively engageable with said stationary element when said control arm is shifted in either direction to position said valve member in either of said active positions and limit stop means engageable with said lever during movement thereof in either direction by movementof said support, thereby disengaging said latching means and permitting said valve member to be shifted to said neutral position by said biasing means acting through said pair of arms.

7. In hydraulic mechanism, the combination of a fluid pressure motor comprisingan extensible cylinder and piston assembly, a control valve therefor including a member shiftable in relatively opposite directions from an intermediate neutral or inactive position to a pair of active positions effecting extension and contraction of said cylinder and piston assembly, respectively, means controlling said valve member comprising a control arm shiftable angularly about an axis, alever connected to said control arm for shifting the latter, a support on which said lever is swingably mounted, means rotatably supporting said support, means] connecting said suppo'rtto said motor to be rotated thereby to shift said lever by movement of said cylinder and piston assembly while said lever is in either of said active positions in the same direction in which said lever in a position to be straddled by said pair of arms,

a normally stationary element mounted adjacent said control arm on means shiftable responsive to an increase of pressure in said supply duct above a predetermined value, said pair of arms straddling both said stop means and said normally stationary element, and having biasing means urging said pair of arms in opposed gripping engagement therewith, each of said pair of arms having means alternatively engageable with said stationary element when said control arm is shifted in either direction to position said valve member in either of said active positions, either of said engageable means beingdisabled by shifting movement of said element to permit said biasing means acting through said pair of arms to return said control arm and valve member to said intermediate inactive position, and limit stop means engageable with said lever during movement thereof in either direction by movement of said support, thereby disengaging said latching means and permitting said valve member to be shifted to said intermediate inactive position by said biasing means acting through said pair of arms.

8. In hydraulic mechanism, a swingably mounted control valve operating arm, an excess pressure relief valve including a shiftable valve member and biasing means normally holding said member stationary, a pair of arms pivotally mounted on said operating arm, a stop mounted onsaid operating arm between said pair of arms, a normally stationary latch element secured to said relief valve and positioned between said'pair of arms, and second biasing means urging said arms together in gripping relation to said latch element, said arms having recesses adapted to engage said element after said operating arm has been swung a predetermined amount in either direction, respectively, for yieldably holding the same, said element being disengageable from either of said recesses when said valve member is shifted against'the pressure of said second biasingmeans.

9. In hydraulic mechanism, the combination of a fluid pressure motor having a movable part; i

a control valve for the motor shiftable in relatively opposite directions between active and inactive positions, selectively, to effect starting and stopping of the motor part; a support movable relative to the motor and having connection to the motor part to be moved by movement of said part; a lever connected to the valve and carried by the support for movement independently of said support from an inactive position to an active position and return for shifting the valve, said lever 'further being movable with the sup- 7 port as the support moves with the motor part;

means for retaining the lever in its active position, including releasable elements arranged to be overcome by force tending to return the lever toward its inactive j position; limit means positionable to intercept the lever upon movement thereof to its active position while permitting. movement of the support by the motor part relative to the lever, said limit means being so arranged relative to the lever and support that movement of the support after interception of the lever reverses the lever and applies such force as the aforesaid to release the elements of the retaining means; and means biasing the valve and leverto. their inactive positions.

10. In hydraulic mechanism, the combination of: a fluid pressure motor having a movable along a linearpath part; a control valve for the motor shiftable in relatively opposite directions between active andinactive positions, selectively, to effect starting and stopping of the motor part; a support movable relative to the motor about a journaling axis and having connection to the motor. part tobe moved angularly about said axis bymovement of said part; a lever connected to the valve and pivoted on the support for. moveactive position to an active position and return for shifting the valve, said lever further being movable with the support as the support is moved angularly by the motor part; means for retaining the lever in its active position, including releasable elements arranged to be overcome by force ten-ding toreturn the lever toward its inactive position; limit means positionable to intercept the lever upon movement thereof to its active position while permitting angular movement of the support by the motor part relative to the lever, said limit means being so arranged relative to the lever and support that continued ment independently of said support from an inangular movement of the support after interception of the lever reverses the lever and applies such force as the aforesaid to release the elements of the retaining means; and means biasing the valve and lever to their inactive positions.

' VIRGINIA F. COURT, Executria: of the Estateof Frank T. Court, De-

ceased.

REFERENCES CITED The following references are of record in the file of this patent:

. UNITED STATES PATENTS 

